Modern Research Center for Traditional Chinese Medicine, School of Chinese Materia Medica, Beijing University of Chinese Medicine, East Road of North 3rd Ring, Chaoyang District, Beijing 100029, China.
State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Avenida da Universidade, Taipa 999078, Macao.
Anal Chem. 2021 Nov 23;93(46):15381-15389. doi: 10.1021/acs.analchem.1c03127. Epub 2021 Nov 13.
Albeit frequently being overlooked, MS spectrum variation against collision energy (CE) implies auxiliary structural clues for / values. Online energy-resolved MS (ER-MS) provides the opportunity to acquire the trajectory of ion intensity against CE for any fragment ion of interest, thus exactly offering the desired momentum to empower the conventional MS spectrum at a certain CE forward to a full-CE ramp MS spectrum (FCER-MS). Efforts were made here to construct an FCER-MS spectrum and to evaluate its potential toward structural analysis. Flavonoids were employed as a proof of concept. MS spectra of 76 compounds were recorded by LC-Q-Exactive-MS, and online ER-MS was subsequently programmed using LC-Qtrap-MS to build a breakdown graph for each obvious fragment ion. After defining the greatest value amongst all regressive apices as 100%, the normalized breakdown graphs comprised an FCER-MS spectrum for each compound. The FCER-MS spectrum contained the MS spectrum at any CE as well as optimal CE (OCE) and maximal relative ion intensity (RII) of each fragment ion. Except the pronounced isomeric discrimination potential, either OCE or RII reflected certain structural properties, such as aglycone, glycosidic bond, and hydroxy, methoxy, and glycosyl substituents. These rules were subsequently applied for flavonoid-focused characterization of a famous herbal medicine, namely Scutellariae Radix, and high-level structural annotation was accomplished for 75 flavonoids. Above all, the FCER-MS spectrum includes /, OCEs, and RII features, thus facilitating confidence-advanced structural analysis.
尽管经常被忽视，但 MS 谱对碰撞能 (CE) 的变化暗示了辅助结构线索和/或值。在线能量分辨 MS (ER-MS) 提供了机会，可针对任何感兴趣的碎片离子获取离子强度随 CE 的轨迹，从而正好为在特定 CE 下向前推进的常规 MS 谱提供所需的动量，以实现全 CE 斜坡 MS 谱 (FCER-MS)。这里努力构建了一个 FCER-MS 谱，并评估了其对结构分析的潜力。黄酮类化合物被用作概念验证。使用 LC-Q-Exactive-MS 记录了 76 种化合物的 MS 谱，随后使用 LC-Qtrap-MS 编程在线 ER-MS，为每个明显的碎片离子构建一个分解图。在将所有回归顶点中的最大值定义为 100%之后，归一化的分解图包含了每个化合物的 FCER-MS 谱。FCER-MS 谱包含了任何 CE 的 MS 谱以及每个碎片离子的最佳 CE (OCE) 和最大相对离子强度 (RII)。除了明显的异构体鉴别潜力外，OCE 或 RII 反映了某些结构特性，例如糖苷配基、糖苷键、羟基、甲氧基和糖基取代基。这些规则随后被应用于著名草药黄芩的黄酮类化合物的特征描述，并对 75 种黄酮类化合物进行了高水平的结构注释。最重要的是，FCER-MS 谱包括/、OCEs 和 RII 特征，从而促进了置信度高的结构分析。
